A couple of gaping plot holes, a fairly unlikeable main character, and WAY too many repetitions of the word 'heap' for a start. As in 'heaps of fun' and 'piled into a heap' and 'a heap of toast'. What is it with me and the word 'heap'? I wasn't even aware I liked the word, and I certainly can't stand it now.
I think at the time I was too keen to get it sent out, worried the agent might think I wasn't up to the task of completing another novel if I messed around for too long - but with hindsight I should have waited a while.
Luckily the holes are easily plugged, and the word 'heap' has been banished forever, but once I've finished the rewrite I'm going to take the advice I've read so many times before, and print the whole thing out for a final read-through (our printer is dodgy so this option never really appealed before).
THEN I'll shove it under a cushion and let it rest for a bit.
After that, I'll send it back knowing it really IS the best it could possibly be; and hope Lovely Agent agrees.